[aprssig] aprssig Digest, Vol 153, Issue 12

K1LPI k1lpi at yahoo.com
Mon Mar 20 14:20:35 EDT 2017

I do a lot of road trips, long ones, and my friends and family like to follow the little red truck on findu and google maps. It would be handy if they could interrogate the radio remotely for posit and status data. Recently I have been involved in some large public events and we used aprs to track our vehicles as the followed a route or moved around the desert in  SAR mode. 

We found that frequent collisions on the frequency lost a lot of packets and our maps were not updating. So I had the idea of trying to implement a transponder mode whereby we could sequentially query each vehicle and have the vehicle send it's position report in the reply message. 

I did find in the APRS SPEC 1.1 "Chapter 15: Station Capabilities, Queries and Responses"a reference to using an Igate to send a 
"APRSP" Directed Query to an individual station for its position, the station should reply with it's Station’s position.
This poses a few issues. We don't really need an Igate. The only IP network is a LAN and a few WiFi routers.  Can we "spoof" the igate in some way so that the rf transmissions from net control to the vehicles APRS radios look like they came from an Igate?
I'm also not sure if the trackers or radios we have will respond to the queries. Does anyone know which trackers or radios have implemented this protocol?  

For experimentation I have a Kenwood D700. I can add the RC-D710 control head to get D-710 capability (or most of it?). I also have a Kenwood TH-D72. 

This might turn out to be an interesting project.
73 de Dave, K1LPI

Message: 2
Date: Sun, 19 Mar 2017 16:40:46 +0000 (UTC)
From: K1LPI <k1lpi at yahoo.com>
To: "aprssig at tapr.org" <aprssig at tapr.org>
Subject: [aprssig] Auto-response position reports
Message-ID: <961062914.3197887.1489941646489 at mail.yahoo.com>
Content-Type: text/plain; charset="utf-8"

Is there a way to interrogate an APRS radio to send it's position in response to a message or "ping" from a another station? In effect, a "transponder" mode. I was thinking a message followed by an automatic reply message might work but I don't see how to include the surrent position in the reply message.
Dave, K1LPI-1 Videbat esse notitia bona id temporis

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